Process for manufacturing aluminum strip or sheet having improved weldability

Abstract

In order to improve the weldability of aluminum strip or sheet by spot welding and to promote the use of these materials, in particular in the bodywork of automobiles, the strip or sheet, after being hot and cold rolled to an intermediate thickness of 1.5 to 2.5 times the final gauge, is etched in an alkaline solution, then cold rolled to final gauge using cold rolling lubricant and finally, if desired, heat treated.

What is claimed is: 
     
       1. A process for manufacturing aluminum sheet or strip characterized by improved weldability comprising: rolling said aluminum sheet or strip to an intermediate thickness of from about 1.5 to 2.5 times the final gauge;   etching said rolled sheet or strip in an alkaline solution; and   rolling said etched sheet or strip to final gauge.   
     
     
       2. A process according to claim 1 wherein said aluminum sheet or strip is hot and cold to said intermediate thickness. 
     
     
       3. A process according to claim 1 wherein said aluminum sheet or strip is rolled to final gauge using a rolling lubricant. 
     
     
       4. A process according to claim 11 wherein said aluminum sheet or strip is cold rolled to final gauge. 
     
     
       5. A process according to claim 11 wherein said aluminum sheet or strip is cold rolled to final gauge using a cold rolling lubricant. 
     
     
       6. A process according to claim 1 further including the steps of heat treating said aluminum sheet or strip after rolling to said final gauge. 
     
     
       7. A process according to claim 1 wherein said aluminum sheet or strip comprises an aluminum alloy consisting essentially of 0.4-1.5% magnesium, 0.3-1.5% silicon, 0-0.03% copper, 0-0.5% iron, 0-1.0% manganese, balance aluminum. 
     
     
       8. A process according to claim 1 wherein said aluminum sheet or strip comprises an aluminum alloy consisting essentially of 0.3-6% magnesium, 0-1.0% manganese, 0-0.4% silicon, 0-0.4% iron, 0-0.2% copper, 0-0.5% chromium, balance aluminum. 
     
     
       9. A process according to claim 1 wherein said aluminum sheet or strip comprises an aluminum alloy consisting essentially of 1.0-5.0% copper, 0.4-2.5% magnesium, 0-0.8% silicon, 0-0.7 % iron, 0-1.5% manganese, balance aluminum. 
     
     
       10. A process according to claim 1 wherein the etching is carried out in an alkaline solution consisting of caustic soda, polyphosphate, wetting agents and inhibitors. 
     
     
       11. A process according to claim 1 further including the steps of welding said aluminum sheet or strip into automobile body sheet. 
     
     
       12. A process according to claim 11 wherein said aluminum sheet or strip is spot welded.